A number of patents disclose certain N-aryl-N-(1-substituted-4-piperidinyl)amides having analgesic activity. For example, U.S. Pat. No. 3,998,834 and 3,164,600, issued to Janssen et al. and assigned to Janssen Pharmaceuticals N. V., disclose certain N-phenyl-N-[N-(aryl-substituted)-4-piperidinyl]-amide compounds and N-aryl-N-[N-(arylalkyl)-4-piperidinyl]amines, respectively, useful as analgesics. U.S. Pat. No. 4,584,303, issued to Huang et al. and assigned to The BOC Group, Inc., discloses certain N-phenyl-N-[N-(heterocyclic)-4-piperidinyl]amide compounds useful as analgesics.
C. R. Ganellin et al., J. Med. Chem., 8, pp. 619-625 (1965) disclose the preparation of N-arylalkyl-3-methyl-4-piperidone derivatives. G. Stork et al., J. Amer. Chem Soc., 68, pp. 1053-1057 (1946) disclose the preparation of N-benzoyl-3-ethyl-3-carboethoxy-4-piperidone derivatives. N. J. Harper et al., J. Med. Chem., 7, pp. 726-728 (1964) disclose the preparation of certain 1-substituted-3,5-dimethyl-4-piperidinols which have no activity compared to the 1, 2, 5 and 1, 2, 3-trimethyl substituted piperidinols. Curwain et al., J. Med. Chem., 7 pp.737-741 (1964) disclose the preparation of certain N-(guanidinoalkyl)pyrrolidine derivatives. C. Mannich et al., Beilstein. 69. pp. 2299-2305 (1936), discloses generally substituted-3,5-dialkyl-4-piperidone derivatives. V. V. Kuznetsov et al., Khim. Geterotsikl Soedin, 7, pp. 949-953 (1987), disclose 1-substituted 4-(N-aryl(alkyl)amino)-2,5-dimethyl-piperidines and their N-acyl derivatives having analgesic activity.